EP3046986B1

EP3046986B1 - Method of inhibiting fouling on a metallic surface using a surface modifying treatment agent

Info

Publication number: EP3046986B1
Application number: EP14809147.3A
Authority: EP
Inventors: Terry D. Monroe; Naima Bestaoui-Spurr; Sumit Bhaduri; Qi Qu
Original assignee: Baker Hughes Holdings LLC
Current assignee: Baker Hughes Holdings LLC
Priority date: 2013-09-20
Filing date: 2014-09-19
Publication date: 2020-07-22
Anticipated expiration: 2034-09-19
Also published as: CA2923221A1; US20190234184A1; US10227846B2; CN105555903B; EP3046986A2; MX2016003340A; RU2016115075A; BR112016005706B1; US20150083397A1; NZ717494A; BR112016005706A2; NZ751779A; CN105555903A; AU2014321304A1; WO2015042488A2; SA516370765B1; CA2923221C; US10704365B2; WO2015042488A3; RU2679399C2

Description

Field of the Disclosure

The disclosure relates to a method of inhibiting fouling during production of fluids from an underground reservoir onto a metallic tubular, flow conduit or vessel by applying onto the surface of the metallic tubular, flow conduit or vessel a treatment agent having an anchor and a hydrophobic tail.

Background of the Disclosure

Fluids produced from underground reservoirs are generally complex mixtures of materials such as aliphatic hydrocarbons, aromatic hydrocarbons, heteroatomic molecules, anionic and cationic salts, acids, sands, silts and clays. The nature of these fluids, combined with the severe conditions of heat, pressure, and turbulence to which they are often subjected, are contributory factors to the formation and deposition of contaminants, such as scales, salts, paraffins, corrosion, asphaltenes and bacteria in underground reservoirs. In particular, such contaminants are deposited onto equipment and flow conduits used in hydrocarbon producing wells and non-hydrocarbon producing wells.
Corrosion of metallic surfaces during such treatments is a prominent issue, as evidenced by surface pitting, embrittlement and loss of metal. For instance, in such well stimulation techniques as pickling, acid washing, matrix acidizing and acid fracturing, the acidic nature of the treatment fluid causes the production or workover conduits in the well to encounter considerable acidic corrosion.
Further, aqueous fluids, such as those used in drilling and completion, have a high salt content which cause corrosion. Gases, such as carbon dioxide and hydrogen sulfide, also generate highly acidic environments to which metallic surfaces become exposed. For instance, corrosion effects from brine and hydrogen sulfide are seen in flow lines during the processing of gas streams. The presence of methanol, often added to such streams to prevent the formation of undesirable hydrates, further often increases the corrosion tendencies of metallic surfaces.
Further, naturally occurring and synthetic gases are often conditioned by treatment with absorbing acidic gases, carbon dioxide, hydrogen sulfide and hydrogen cyanide. Degradation of the absorbent and acidic components as well as the generation of by-products (from reaction of the acidic components with the absorbent) results in corrosion of metallic surfaces.
The deposition of scales and asphaltenes further presents problems as they reduce well productivity and shorten the lifetime of production equipment. In order to clean such deposits from wells and equipment it is necessary to stop the production which is both time-consuming and costly.
It is fairly common during such oilfield treatment processes to use treatment agents to inhibit or prevent the formation of such contaminants. Many conventional inhibitors, however, are becoming unacceptable for use in oilfield treatment processes due to environmental protections measures which have been undertaken. Alternative solutions to address the inhibition of formation of such contaminants have been sought.
US 2009/114247 A1 refers to a method of removing unwanted deposits from a surface of a flow conduit or vessel comprising a foaming agent and a treatment agent, such as a scale inhibitor, corrosion inhibitor, salt inhibitor, scale remover or biocide, wherein a thin film concentrate of the treatment agent is coated over at least a portion of the surface.
US 2012/318515 A1 refers to a method of inhibiting or controlling the rate of release of a well treatment agent in a well, a subterranean formation, a flow conduit or a vessel by introducing into the well, subterranean formation, flow conduit or vessel the well treatment agent in a microemulsion.
US 2012/325485 A1 refers to a method of enhancing the productivity of a hydrocarbon bearing siliceous or calcareous formation by use of a well treatment composition which contains a phosphonate acid, ester or salt, a hydrofluoric acid source, a quaternary ammonium salt and an organosilane.
US 2009/011248 A1 refers to the use of transition metal-silicon containing reaction products as coatings for various substrates, especially to a non-particulate substrate having adhered thereto a coating comprising the reaction product of (a) a transition metal compound and a transition metal compound in which the transition metal has electrons in the f orbital, and (b) a silicon-containing material.
US 2009/324834 A1 refers to a composition for providing a hydrophobic coating to a metal substrate comprising (a) a perfluorinated acid capable of forming a self-assembled monolayer on the metal substrate, (b) a surfactant, (c) an organic solvent, and (d) water.

Summary of the Disclosure

The invention is set out in the appended set of claims.

Detailed Description of the Preferred Embodiments

Characteristics and advantages of the present disclosure and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of exemplary embodiments of the present disclosure and referring to the accompanying figures. It should be understood that the description herein and appended drawings, being of example embodiments, are not intended to limit the claims of this patent or any patent or patent application claiming priority hereto. Many changes may be made to the particular embodiments and details disclosed herein without departing from the scope of the claims.
Certain terms are used herein and in the appended claims may refer to particular components, process steps or well treatment operations. As one skilled in the art will appreciate, different persons may refer to a component, a process step or a well treatment operation by different names. This document does not intend to distinguish between components, process steps or well treatment operations that differ in name but not function or operation. Also, the terms "including" and "comprising" are used herein and in the appended claims in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to ...." Further, reference herein and in the appended claims to components and aspects in a singular tense does not necessarily limit the present disclosure or appended claims to only one such component or aspect, but should be interpreted generally to mean one or more, as may be suitable and desirable in each particular instance.
Preferred embodiments of the present disclosure thus offer advantages over the prior art and are well adapted to carry out one or more of the objects of this disclosure. However, the present disclosure does not require each of the components and acts described above and are in no way limited to the above-described embodiments or methods of operation.
In an embodiment, the disclosure relates to a method of using a surface modifying treatment agent to inhibit deposition or accumulation of contaminants onto a metallic surface of a tubular, flow conduit or vessel located within an underground reservoir or extending from or to an underground reservoir. The flow conduit may be a surface pipeline or flow line. The method may be used to inhibit the deposition or accumulation of vessels located on the fly. The method may further be used to inhibit the deposition or accumulation of contaminants onto flow conduits and vessels used in refineries and fluid processing facilities.
The underground reservoir referred to herein may be a hydrocarbon producing well or a non-hydrocarbon producing well. For instance, the underground reservoir may be a gas producing well, an oil producing well, a geothermal well, a coal bed methane well or a water injection well.
The surface modifying treatment agent may be applied onto the metallic surface of the tubular, flow conduit or vessel prior to entry of the tubular, flow conduit or vessel into an underground reservoir, though typically the surface modifying treatment agent is pumped into the reservoir after placement of the tubular, flow conduit or vessel within the reservoir.
The surface of the tubular, flow conduit or vessel is typically composed of metals such as carbon steel or high alloy steels including chrome steels, duplex steels, stainless steels, martensitic alloy steels, ferritic alloy steels, austenitic stainless steels, precipitation-hardened stainless steels or high nickel content steels.
The surface modifying treatment agent comprises an anchor and a hydrophobic tail. The anchor serves to bond the hydrophobic tail onto a reactive group on the metallic substrate. In a preferred embodiment, the hydrophobic tail is not directly bond, attached or secured to the metallic substrate or to the reactive group on the metallic substrate. The hydrophobic tail of the surface modifying treatment agent is only indirectly attached to the substrate through the anchor. The hydrophobic tail is typically directed away from the metallic surface. The hydrophobic tail is believed to facilitate the movement of aqueous fluids within the reservoir away from the metallic surface of the tubular, flow conduit or vessel. This may be attributable to the modification in wettability imparted to the metallic surface by the hydrophobic tail.
The thickness of the surface modifying treatment agent on the metallic tubular, flow conduit or vessel is typically between from about 2 to about 40 nanometers. While not being bound by any particular theory, it is believed that a covalent bond is formed between the solid particulate (such as the metal of the oxide on the tubular, conduit or vessel) and the anchor of the surface modifying treatment agent.
The surface modifying treatment agent, when attached onto the tubular, conduit or vessel through the metal oxide is highly stable. Inhibition of fouling due to contaminants onto the metal surface persists throughout the extended lifetime of the bond surface modifying treatment agent.
The hydrophobic tail of the surface modifying treatment agent repels aqueous fluid within the reservoir away from the metallic substrate of the tubular, flow conduit or vessel. Direct contact time between the aqueous fluid containing contaminants and the metallic substrate of the tubular, flow conduit or vessel is decreased.
While the tail of the surface modifying treatment agent exhibits hydrophobic characteristics, it may also exhibit oleophobic properties. The surface modifying treatment agent may therefore be considered to be omniphobic.
The surface modifying treatment agent may also be used to passively inhibit, control, or prevent deposition or accumulation of scales, rust, paraffin, asphaltenes, salt or bacteria (aerobic and anaerobic) and other microbials onto the metallic substrate. (As used herein the term "inhibition" or "inhibit" shall include controlling or preventing the deposition or accumulation of contaminants onto metallic substrates.) Such inhibition may be attributable to the hydrophobic tail of the surface modifying treatment agent which minimizes or decreases the ability of contaminants to adhere to the metallic substrate of the tubular, flow conduits or vessel within the reservoir.
Further, the inhibition in scale deposition may be attributable to the hydrophobic nature of such minerals like calcium, barium, magnesium salts and the like including barium sulfate, calcium sulfate, and calcium carbonate as well as metal sulfides like zinc sulfide, iron sulfide, etc.
The bulky nature of the hydrophobic tail of the composites further may assist, prevent or control deposition of organic particulates onto the metallic substrate.
Corrosive effects of metal, especially iron and ferrous base metals, may be inhibited or prevented in light of the hydrophobicity of the surface modifying treatment agent when adhered to the metallic substrate.
The surface modifying treatment agent may further serve a passive antimicrobial function in order to counter bacterial growth principally caused by nitrogen and/or phosphorus in formation water or within fluid injected into the formation. The hydrophobic tail of the surface modifying treatment may repel the fluid from the metal surface and thus decreases contact time of the fluid onto the metallic surface. This prevents the build-up of aerobic bacteria, anaerobic bacteria and other microbials.
In a preferred embodiment, the anchor of the surface modifying treatment agent may be an organophosphorus acid derivative with the hydrophobic group attached to the anchor. In another preferred embodiment, the anchor of the surface modifying treatment agent may be a metal and the hydrophobic tail may be an organo-silicon material, a fluorinated hydrocarbon or both an organo-silicon material and a fluorinated hydrocarbon.

Organophosphorus as Anchor

The organophosphorus acid derivative comprising the anchor of the surface modifying treatment agent may originate from an organophosphoric acid, organophosphonic acid or organophosphinic acid. The organo groups of the anchor may be monomeric or polymeric.
Examples of monomeric phosphoric acid derivatives are compounds or mixtures of compounds having the structure (RO)_x-P(O)-(OR')_y wherein x is 1-2, y is 1-2 and x+y=3; R preferably is a radical having a total of 1-30, preferably 2-20, more preferably 6-18 carbons; R' is H, a metal such as an alkali metal, for example, sodium or potassium or lower alkyl having 1 to 4 carbons, such as methyl or ethyl. Preferably, a portion of R' is H. The organic component of the phosphoric acid (R) can be a saturated or unsaturated aliphatic group or can be an aryl or aryl-substituted moiety. At least one of the organo groups can contain terminal or omega functional groups as described below.
Examples of monomeric phosphonic acid derivatives include compounds or mixtures of compounds having the formula:
wherein a is 0-1, b is 1, c is 1-2 and a+b+c is 3; R and R" preferably are each independently a radical having a total of 1-30, preferably 2-20, more preferably 6-18 carbons; R' is H, a metal, such as an alkali metal, for example, sodium or potassium or lower alkyl having 1-4 carbons such as methyl or ethyl. Preferably at least a portion of R' is H. The organic component of the phosphonic acid (R and R") can be a saturated or unsaturated aliphatic group or an aryl or aryl-substituted moiety. At least one of the organo groups can contain terminal or omega functional groups as described below.
Examples of monomeric phosphinic acid derivatives are compounds or mixtures of compounds having the formula:
wherein d is 0-2, e is 0-2, f is 1 and d+e+f is 3; R and R" preferably are each independently radicals having a total of 1-30, preferably 2-20 carbons atoms, more preferably 6-18 carbons; R' is H, a metal, such as an alkali metal, for example, sodium or potassium or lower alkyl having 1-4 carbons, such as methyl or ethyl. Preferably a portion of R' is H. The organic component of the phosphinic acid (R, R") can be a saturated or unsaturated aliphatic group or be an aryl or aryl-substituted moiety. Examples of organo groups which may comprise R and R" include long and short chain aliphatic hydrocarbons, aromatic hydrocarbons and substituted aliphatic hydrocarbons and substituted aromatic hydrocarbons.
At least one of the organo groups can further contain one or more terminal or omega functional groups which are hydrophobic. Examples of terminal or omega functional groups include carboxyl such as carboxylic acid, hydroxyl, amino, imino, amido, thio and phosphonic acid, cyano, sulfonate, carbonate and mixed substituents.
Representative of organophosphorus acid derivatives are amino trismethylene phosphonic acid, aminobenzylphosphonic acid, 3-amino propyl phosphonic acid, O-aminophenyl phosphonic acid, 4-methoxyphenyl phosphonic acid, aminophenylphosphonic acid, aminophosphonobutyric acid, aminopropylphosphonic acid, benzhydrylphosphonic acid, benzylphosphonic acid, butylphosphonic acid, carboxyethylphosphonic acid, diphenylphosphinic acid, dodecylphosphonic acid, ethylidenediphosphonic acid, heptadecylphosphonic acid, methylbenzylphosphonic acid, naphthylmethylphosphonic acid, octadecylphosphonic acid, octylphosphonic acid, pentylphosphonic acid, phenylphosphinic acid, phenylphosphonic acid, styrene phosphonic acid, and dodecyl bis-1,12-phosphonic acid.
In addition to monomeric organophosphorus acid derivatives, oligomeric or polymeric organophosphorus acid derivatives resulting from self-condensation of the respective monomeric acids may be used.
The hydrophobic tail of the surface modifying treatment agent may be a fluorine containing moiety. In an embodiment, the fluorine containing moiety is R_f-(CH₂)_p- where R_f is a perfluorinated alkyl group or contains a perfluorinated alkylene ether group and p is 2 to 4, preferably 2.
Typically, the fluorine containing moiety has a number average molecular weight of less than 2000.
Examples of perfluorinated groups for the fluorine containing moiety are those of the structure:
where Y is F or C_nF_2n+1; m is 4 to 20 and n is 1 to 6.
A preferred oligomeric or perfluoroalkylene ether group is where R and/or R" is a group of the structure:
where A is an oxygen radical or a chemical bond such as CF₂; n is 1 to 20, preferably 1 to 6; Y is H, F, C_nH_2n+1 or C_nF_2n+1; b is at least 1, preferably 2 to 10, m is 0 to 50, and p is 1 to 20.
In a preferred embodiment, the surface modifying treatment agent is of the formula R_f-(CH₂)_p-Z where Z, the attachment site is H, F or an acid derivative, and the hydrophobic tail (bonded to the attachment site) is the R_f-(CH₂)_p- moiety where R_f is a perfluorinated alkyl group or contains a perfluorinated alkylene ether group referenced above and p is 2 to 4, preferably 2.
In an embodiment, the surface modifying treatment agent is of the formula R_f-(CH₂)_p-Z, wherein Z is:
where R and R" are a hydrocarbon or substituted hydrocarbon radical having up to 200, such as 1 to 30 and 6 to 20 carbons, R and R" can also include the perfluoroalkyl groups mentioned above, and R' is H, a metal such as potassium or sodium or an amine or an aliphatic radical, for example, alkyl including substituted alkyl having 1 to 50 carbons, preferably lower alkyl having 1 to 4 carbons such as methyl or ethyl, or aryl including substituted aryl having 6 to 50 carbons.
In an embodiment, the surface modifying treatment agent is of the formula CF₃(C_nF2n)CH₂CH₂PO₃H₂ where n is between 3 and 5 or CF₃(CF₂)_xO(CF₂CF₂)_y-CH₂CH₂-PO₃H₂ where x is from 0 to 7, y is from 1 to 20 and x+y is less than or equal to 27.
While not being bound to any theory, it is believed that a covalent bond is formed between the metal of the oxide of the tubular, conduit or vessel and the anchor of the surface modifying treatment agent by breaking the P=O bond of the organophosphorus to form a M-O-P covalent bridge.

Organo-silicon and/or Fluorinated Hydrocarbon As Anchor

The anchor of the surface modifying treatment agent may be a metal. For instance, the anchor may be a Group 3, 4, 5, or 6 metal. In a preferred embodiment, the metal is a Group 4 metal, such as Ti, Zr or Hf, a Group 5 metal, such as Ta or Nb, a Group 6 metal, such as W, or a metal of the lanthanide series, such as La.
The hydrophobic tail of the surface modifying treatment agent may be an organo-silicon material, a fluorinated hydrocarbon or both a hydrophobic organo-silicon material and a fluorinated hydrocarbon.
The surface modifying treatment agent may be represented by the formula X-M, wherein M is the metal containing organic ligand and X is the hydrophobic tail represented by the organo-silicon containing material, the fluorinated hydrocarbon or a combination of organo-silicon containing material and fluorinated hydrocarbon.
The tail of the surface modifying treatment agent may be aligned such that the hydrophobicity character of the treatment agent is imparted away from the anchor.
The surface modifying treatment agent may be formed by reacting a metal containing organic ligand with the organo-silicon containing material and/or fluorinated hydrocarbon group.
The metal containing organic ligand may be formed by reacting a metal compound, such as a metal halide, like TaCl₅, with an oxygen containing ligand. The number of oxygen containing ligands attached to the metal is typically equal to the valency of the metal atom. Thus, depending upon the position of the transition metal on the Periodic Chart, the metal containing organic ligand may have from two to six organic ligand groups.
In an embodiment, the ligand of the metal containing organic ligand contains an alkoxide or ester. Suitable organometallic derivatives include metal derivatives of C₁ to C₁₈ alkoxides, preferably alkoxides containing from 2 to 8 carbon atoms such as ethoxide, propoxide, isopropoxide, butoxide, isobutoxide and tertiary butoxide. For instance, the metal containing organic ligand may be a transition metal tetra-alkoxide, such as zirconium tetra tert-butoxide.
The alkoxides may be in the form of simple esters and polymeric forms of the alkoxylates and esters as well as various chelates and complexes. For example, with the metal Ta, the simple esters could be Ta(OR)₅ where R is C₁ to C₁₈ alkyl. Polymeric esters may be obtained by condensation of an alkyl ester and can have the structure RO--[Ta(OR)₃-O-]_x--R where R is defined above and x is a positive integer.
Further, the alkoxide can include, for instance, when the metal is titanium or zirconium:

(a) alkoxylates having the general formula M(OR)₄, wherein M is selected from Ti and Zr and R is C_1-18 alkyl;
(b) polymeric alkyl titanates and zirconates obtainable by condensation of the alkoxylates of (a), i.e., partially hydrolyzed alkoxylates of the general formula RO[-M(OR)₂O-]_x-1R, wherein M and R are as above and x is a positive integer;
(c) titanium chelates, derived from ortho titanic acid and polyfunctional alcohols containing one or more additional hydroxyl, halo, keto, carboxyl or amino groups capable of donating electrons to titanium. Examples of these chelates are those having the general formula Ti(O)_a(OH)_b(OR')_c(XY)_d, wherein a=4-b-c-d; b=4-a-c-d; c=4-a-b-d; d=4-a-b-c; R' is H, R as above or X-Y, wherein X is an electron donating group such as oxygen or nitrogen and Y is an aliphatic radical having a two or three carbon atom chain such as:
1. (i) -CH₂CH₂-, e.g., of ethanolamine, diethanolamine and triethanolamine, or
2. (ii) lactic acid,
3. (iii) acetylacetone enol form, and
4. (iv) 1,3-octyleneglycol,
(d) titanium acrylates having the general formula Ti(OCOR)_4-n(OR)_n wherein R is C_1-18 alkyl as above and n is an integer of from 1 to 3, and polymeric forms thereof, or
(e) mixtures thereof.

Acetyl acetonates, alkanolamines, lactates and halides, such as chloride, can also be used as the ligand of the oxygen containing organic ligand. In addition, the oxygen containing ligand can contain a mixture of ligands selected alkoxides, acetyl acetonates, alkanolamines, lactates and halides.
In an embodiment, the organo-silicon containing material may be a silane, polysiloxane or a polysilazane.
Examples of organo-silicon containing materials are those having the formula R¹ _4-xSiA_x or (R¹ ₃Si)_yB as well as organo(poly)siloxanes and organo(poly)silazanes containing units of the formula:
where R¹ may be the same or different and is a hydrocarbon radical containing from 1 to 100, such as 1 to 20 carbon atoms and 1 to 12, preferably 1 to 6 carbon atoms and R³ may be hydrogen or a hydrocarbon or substituted hydrocarbon having 1 to 12, preferably 1 to 6 carbon atoms. In addition, R¹ may be a substituted, hydrocarbon radical such as halo, particularly a fluoro-substituted hydrocarbon radical. The organo(poly)siloxane may further contain additional units of the formula: R⁵ ₂SiO₂ where R⁵ is a halogen such as a chloro or fluoro substituent.
In an embodiment, the organo-silicon containing compound may be an organo(poly)siloxane or organo(poly)silazane of a number average molecular weight of at least 400, usually between 1000 and 5,000,000.
The substituent A in R¹ _4-xSiA_x may be hydrogen, a halogen such as chloride, OH, OR² or
wherein B in the above structural formula may be NR³ _3-y, R² a hydrocarbon or substituted hydrocarbon radical containing from 1 to 12, typically 1 to 4 carbon atoms. R³ is hydrogen or has the same meaning as R , x is 1, 2 or 3, y is 1 or 2.
Preferably, R¹ is a fluoro-substituted hydrocarbon. Preferred are such fluoro-substituted hydrocarbons are those of the structure:
where Y is F or C_nF_2n+1; m is 4 to 20 and n is 1 to 6; R² is alkyl containing from 1 to 4 carbon atoms and p is 0 to 18. Also, fluoro-substituted hydrocarbons may be of the structure:
where A is an oxygen radical or a chemical bond; n is 1 to 6, y is F or C_nF_2n; b is at least 1, such as 2 to 10; m is 0 to 6 and p is 0 to 18.
Preferred organo-silicon materials include halogenated siloxanes, halogenated alkoxysiloxanes such as perfluoroalkoxysiloxane (PFOSi), alkoxy halogenated alkoxysilanes, such as alkoxy-perfluoroalkoxysilane; alkoxyacetylacetonate halogenated polysiloxanes, such as alkoxyacetylacetonate-perfluoroalkoxysiloxane, alkoxy-alkylsilylhalides; polyalkylsiloxanes, such as polydimethylsiloxanes, and alkoxyacetylacetonate-polyalkylsiloxanes, such as alkoxyacetylacetonate (acac) polydimethylsiloxanes. Exemplary surface modifying treatment agents include tantalum halide-perfluoroalkoxysiloxane, such as TaCl₅:PFOSi; tantalum alkoxy-perfluoroalkoxysilane; tantalum alkoxyacetylacetonate-perfluoroalkoxysiloxane, like Ta(EtO)₄acac:PFOSi; tantalum alkoxy-alkylsilylhalide; tantalum halide-polyalkylsiloxane, like TaCl₅:PDMS; ; niobium alkoxide-perfluoroalkoxysiloxane, such as Nb(EtO)₅:PFOSi and Ta(EtO)₅:PFOSi; titanium alkoxide-perfluoroalkoxysiloxane, like Ti(n-BuO)₄:PFOSi; zirconium alkoxide-perfluoroalkoxysiloxane; lanthanum alkoxide-perfluoroalkoxysilane, like La(iPrO)₃:PFOSi; tungsten chloride-perfluoroalkoxysiloxane, like WCl₆:PFOSi; tantalum alkoxide-polyalkylsiloxane, like Ta(EtO)₅:PDMS; and tantalum alkoxyacetylacetonate-polyalkylsiloxane, like Ta(EtO)₄acac:PDMS.
In an embodiment, the fluorinated hydrocarbon is R_f-(CH₂)_p-X where R_f is a perfluorinated hydrocarbon group including an oxygen substituted hydrocarbon group, such as a perfluorinated alkyl group or a perfluorinated alkylene ether group and p is 0 to 18, preferably 0-4, and X is a polar group such as a is carboxyl, like of the structure -(C=O)-OR; and R is hydrogen, perfluoroalkyl, alkyl or substituted alkyl containing from 1 to 50 carbon atoms.
Examples of perfluoroalkyl groups are those of the structure F-(CFY-CF₂)_m where Y is F or C_nF_2n+1; m is 4 to 20 and n is 1 to 6.
Examples of perfluoroalkylene ether groups are those of the structure:
where A is an oxygen radical or a chemical bond; n is 1 to 6, Y is F or C_nF_2n; b is 2 to 20, m is 0 to 6, and p is 0 to 18, preferably 2 to 4 and more preferably 2.
Preferred fluorinated materials are esters of perfluorinated alcohols such as the alcohols of the structure F-(CFY-CF₂)_m-CH₂-CH₂-OH where Y is F or C_nF_2n+1; m is 4 to 20 and n is 1 to 6.
Further preferred as fluorinated hydrocarbons are perfluorinated hydrocarbons of the structure R_f-(CH₂)_p-X where R_f is a perfluoroalkylene ether group or a perfluorinated alkyl group such as those described above, p is an integer of from 0 to 18, preferably 0 to 4, and X is a carboxyl group, preferably a carboxylic ester group containing from 1 to 50, preferably from 2 to 20 carbon atoms in the alkyl group that is associated with the ester linkage.
Further preferred as fluorinated hydrocarbons are perfluorinated hydrocarbons of the structure R_f-(CH₂)_p-Z where R_f and p are as defined above, preferably R_f is a perfluoroalkylene ether group such as those described above, and p is from 2 to 4, and Z is a phosphorus acid group. Examples of phosphorus acid groups are:
where R" is a hydrocarbon or substituted hydrocarbon radical having up to 200, such as 1 to 30 and 6 to 20 carbons, R" can also include the perfluoroalkyl groups mentioned above, and R' is H, a metal such as potassium or sodium or an amine or an aliphatic radical, for example, alkyl including substituted alkyl having 1 to 50 carbons, preferably lower alkyl having 1 to 4 carbons such as methyl or ethyl, or aryl including substituted aryl having 6 to 50 carbons.
Preferably, the phosphorus acid is of formula II where R and R' are H.
Suitable methods for preparing the surface modifying treatment agents wherein the organo portion of the metal containing organic ligand is reactive with the organo-silicon containing material or fluorinated hydrocarbon group are disclosed in U.S. Patent No. 7,879,437 and 8,067,103 . In one embodiment, for instance, the organo portion of the organometallic compound may be selected from those groups that may be reactive with the acids (or their derivatives) of a perfluoroalkylene ether.
As an example, the surface modifying treatment agent could be prepared by mixing the metal containing organic ligand and the silicon-containing material or fluorinated hydrocarbon in a closed system to avoid hydrolysis of the reactants. Reaction can occur neat or in the presence of a non-reactive solvent such as chlorinated or fluorinated solvent, for example, methylene chloride. Heat may be used to initiate and complete the reaction. Solvent may be removed by evaporation and the reaction product can be redissolved in a suitable solvent such as an alcohol, for example, ethanol or propanol, for application to the substrate. The mole ratio of the organosilicon-containing material to the metal containing organic ligand is typically from 100:1 to 1:100, preferably from 1:1 to 10:1 depending on the valence of the metal of the metal containing organic ligand. For example, the molar ratio of organosilicon compound to Ta(V) is typically 5 to 1.
In an embodiment, the surface modifying treatment agent may be represented by the formula X_a(OR)_bM, wherein OR is a C₁ to C₁₈ alkoxide, X is the hydrophobic tail represented by the organo-silicon material or the fluorinated hydrocarbon, M is metal of the metal containing organic ligand and a + b equals the valency of M and further wherein neither a nor b are zero.
In an exemplary embodiment, the surface modifying agent may be formed by reacting an organosilicon compound such as an organosilane or a polysiloxane with a metal containing organic ligand, such as a derivatized alkoxide. The metal of the metal containing organic ligand is covalently bonded to the organosilicon compound to form the anchor and the hydrophobic tail.
The attachment site of the anchor of the surface modifying treatment agent onto the metallic substrate is typically a reactive functional group. The reactive group on the metallic substrate typically is a metal oxide.
The metal oxide may also be applied onto the metallic surface of the tubular, flow conduit or vessel by application of a primer. The primer when coated onto the substrate may contain a metal oxide or may form a metal oxide upon contact. While it is possible to mix the primer with the surface modifying treatment agent and apply the mixture to the substrate at the same time, it is more preferred to apply the primer first and then, after reactive functional groups have been formed, apply the surface modifying treatment agent.
The primer may be applied to the metallic substrate by conventional means such as immersion coating such as dipping, rolling, or spraying to form the coating. The diluent is permitted to evaporate. This can be accomplished by heating to 50-200°C.
In a preferred embodiment, a fluid containing an organometallic material may be used to impart reactive functional groups to the metallic substrate. Such functional groups may be reactive with the anchor of the surface modifying treatment agent.
Such organometallic compounds include those derived from a transition metal, such as a Group IIIB metal or a transition metal selected from Group IVB, VB and VIB. Preferred transition metals are titanium, zirconium, lanthanum, hafnium, tantalum and tungsten.
The organo portion of the organometallic may contain an alkoxide and/or halides. Examples of suitable alkoxide groups are those containing from 1 to 18 carbon atoms, preferably 2 to 8 carbon atoms, such as ethoxide, propoxide, isopropoxide, butoxide, isobutoxide and tertiary butoxide. Examples of suitable halides are fluoride and chloride. Other ligands which may also be present are acetyl acetonates.
Suitable organometallic compounds may be esters and polymeric forms of the esters including:

i. alkoxylates of titanium and zirconium having the general formula M(OR)₄, wherein M is selected from Ti and Zr and R is C_1-18 alkyl;
ii. alkyl esters of titanium and zirconium having the general formula (X)_4-y-M(OR)_y, wherein M is selected from Ti and Zr; X is selected from fluorine and chlorine; R is C_1-18 alkyl and y=2 to 3;
iii. polymeric alkyl titanates and zirconates obtainable by condensation of the alkyl esters of (a), i.e., partially hydrolyzed alkyl esters of the general formula RO[-M(OR)(X)O--]_yR, wherein M, R and X are as above and y is a positive integer;
iv. titanium chelates, derived from ortho titanic acid and polyfunctional alcohols containing one or more additional hydroxyl, halo, keto, carboxyl or amino groups capable of donating electrons to titanium. Examples of these chelates are those having the general formula Ti(O)_a(OH)_b(OR%(XY)_d, wherein a=4-b-c-d; b=4-a-c-d; c=4-a-b-d; d=4-a-b-c; R' is H, R as above or X-Y, wherein X is an electron donating group such as oxygen or nitrogen and Y is an aliphatic radical having a two or three carbon atom chain such as:
1. (a) -CH₂CH₂-, e.g., of ethanolamine, diethanolamine and triethanolamine, or
2. (b) lactic acid,
3. (c) acetylacetone enol form, and
4. (d) 1,3-octyleneglycol,
  v. titanium acrylates having the general formula Ti(OCOR)_4-n(OR)_n wherein R is C_1-18 alkyl as above and n is an integer of from 1 to 3, and polymeric forms thereof, or vi. mixtures of (a) and (b).

The organometallic compound is usually dissolved or dispersed in a diluent. Examples of suitable diluents are alcohols such as methanol, ethanol and propanol, aliphatic hydrocarbons, such as hexane, isooctane and decane, ethers, for example, tetrahydrofuran and dialkyl ethers such as diethyl ether. Alternatively, the organometallic compound may be applied to the solid particulate by vapor deposition techniques.
The concentration of the organometallic compound in the composition is not particularly critical but is usually at least 0.001 millimolar, typically from 0.01 to 100 millimolar, and more typically from 0.1 to 50 millimolar.
In addition, a metal oxide may be deposited onto the metallic surface from precipitation of oxides from a solution.
Further, the metal oxide may form on the metallic surface such as through corrosion or such environmental factors as air or water. Further, the metal oxide may be deposited onto the metallic surface by precipitation or formation of scales, rust, paraffin, asphaltenes or salts within the reservoir. Application of the surface modifying treatment agent onto the metallic surface of the tubular, flow conduit or vessel inhibits further precipitation or formation of such deposits.
The surface modifying treatment agent may be dissolved or dispersed in a diluent to form a solution. The solution may then be applied onto the metallic substrate. Suitable diluents include alcohols such as methanol, ethanol or propanol; aliphatic hydrocarbons such as hexane, isooctane and decane, ethers, for example, tetrahydrofuran and dialkylethers such as diethylether. Diluents for fluorinated materials can include perfluorinated compounds such as perfluorinated tetrahydrofuran. Also, aqueous alkaline solutions such as sodium and potassium hydroxide can be used as the diluent.
The concentration of the surface modifying treatment agent in a fluid pumped into the reservoir is typically between from about 0.01% to 100% or more typically between from about 0.1 % to about 20%> (v/v).
The surface modifying treatment agent may also be pumped into the reservoir as a component of a fluid. Thus, for instance, the surface modifying treatment agent may be pumped into the reservoir as a component of a fracturing fluid, pad fluid, acidizing fluid, etc.

Claims

A method of inhibiting fouling caused by contaminants onto a metallic tubular, flow conduit or vessel in an underground reservoir or extending from or to an underground reservoir, the method comprising:
(a) introducing onto a metal oxide on the metallic tubular, flow conduit or vessel a surface modifying treatment agent comprising an anchor and a hydrophobic tail, wherein either
(i) the anchor is a metal
and
the hydrophobic tail is an organo-silicon material, a fluorinated hydrocarbon or both an organo-silicon material and a fluorinated hydrocarbon; or

(ii) the anchor is an organophosphoric acid, organophosphonic acid or organophosphinic acid and the hydrophobic tail is attached thereto,
wherein the surface modifying treatment agent is
of the formula:

R_f-(CH₂)_p-Z

wherein:
R_f is a perfluorinated alkyl group or a perfluorinated alkylene ether group; p is 2 to 4; and

Z is selected from the group consisting of:
wherein R and R" are a hydrocarbon or substituted hydrocarbon radical having up to 200 carbon atom or a perfluoroalkyl group, and R' is H, a metal, an amine or an aliphatic or aryl radical; or
CF₃(C_nF_2n)CH₂CH₂PO₃H₂ where n is between 3 and 5, and CF₃(CF₂)_xO(CF₂CF₂)_y-CH₂CH₂-PO₃H₂ where x is from 0 to 7, y is from 1 to 20 and x+y is less than or equal to 27;

(b) attaching the anchor onto at least a portion of the metal oxide; and

(c) inhibiting fouling from a fluid onto the tubular, flow conduit or vessel by exposing the fluid to the hydrophobic tail.
The method of claim 1, wherein the anchor is an organophosphoric acid, organophosphonic acid or organophosphinic acid and the hydrophobic tail is directed away from the metal oxide.
The method of claim 1, wherein either:
(a) the flow conduit is a surface pipeline or flow line;

(b) the anchor of the surface modifying treatment agent is bound to the metal oxide on the metallic tubular, flow conduit or vessel prior to introducing the metallic tubular, flow conduit or vessel into the underground reservoir; or

(c) the anchor of the surface modifying treatment agent is bound to the metal oxide on the metallic tubular, flow conduit or vessel in-situ within the underground reservoir.
The method of claim 2, wherein the surface modifying treatment agent is at least one member selected from the group consisting of:
(a) a derivative of a phosphoric acid having the structure (RO)_x-P(O)-(OR')_y;.

(b) a derivative of a phosphonic acid of the structure:
and

(c) a derivative of a phosphinic acid of the structure:
wherein:
R and R" are each independently a radical having a total of 1 to 30 carbon atoms; R' is H, a metal or a lower alkyl having from 1 to 4 carbon atoms;

x is 1 to 2; y is 1 to 2; x+y=3;

a is 0-1;

b is 1;

c is 1-2;

a+b+c is 3;

d is 0-2;

e is 0-2;

f is 1; and

d+e+f is 3.
The method of claim 1, wherein either:
(a) the fluorinated hydrocarbon is of the structure:
where Y is F or C_nF_2n+1; m is 4 to 20 and n is 1 to 6; R² is alkyl containing from 1 to 4 carbon atoms and p is 0 to 18;

(b) the metal of the anchor is a Group 3, 4, 5, or 6 metal; or

(c) the hydrophobic organo-silicon material contains additional units of the formula: R⁵ ₂SiO₂ where R⁵ is halogen.
The method of claim 1, wherein the fluorinated hydrocarbon is of the structure:
where A is an oxygen radical or a chemical bond; n is 1 to 6, y is F or C_nF_2n; b is at least 1; m is 0 to 6 and p is 0 to 18.
The method of claim 1, wherein the hydrophobic organo-silicon material is an organo(poly)siloxane or an organo(poly)silazane.
The method of claim 7, wherein the organo(poly)siloxane or the organo(poly)silazane have units of the formula:
where R¹ are identical or different and are a hydrocarbon or substituted hydrocarbon radical containing from 1 to 12 carbon atoms; and R³ is hydrogen or R¹.
The method of claim 1, wherein the hydrophobic organo-silicon material has a formula selected from:
R¹ _4-xSiA_x and (R¹ ₃Si)_yB

or an organo(poly)siloxane or organo(poly)silazane of the formula:
where:
R¹ are identical or different and are a hydrocarbon or substituted hydrocarbon radical containing from 1 to 100 carbon atoms;

A is hydrogen, halogen, OH, OR² or

B is NR³ _3-y;

R² is a hydrocarbon or substituted hydrocarbon radical containing from 1 to 12 carbon atoms;

R³ is hydrogen or R¹;

x is 1, 2 or 3; and

y is 1 or 2.
The method of claim 5, wherein the metal of the surface modifying treatment agent is selected from the group consisting of Ti, Zr, La, Hf, Ta, W and Nb.